Buggy code:
@ SuppressWarnings ( "serial" ) public class ConditionalFormatter implements Serializable { private static final Logger LOGGER = Logger . getLogger ( ConditionalFormatter . class . getName ( ) ) ; private static String BORDER_STYLE_DEFAULT = "1pt<seq2seq4repair_space>solid<seq2seq4repair_space>#d6d6d6;" ; private Spreadsheet spreadsheet ; private Map < String , Set < Integer > > cellToIndex = new HashMap < String , Set < Integer > > ( ) ; private Map < ConditionalFormatting , Integer > topBorders = new HashMap < ConditionalFormatting , Integer > ( ) ; private Map < ConditionalFormatting , Integer > leftBorders = new HashMap < ConditionalFormatting , Integer > ( ) ; protected FormulaEvaluator formulaEvaluator ; protected ColorConverter colorConverter ; public ConditionalFormatter ( Spreadsheet spreadsheet ) { } public Set < Integer > getCellFormattingIndex ( Cell cell ) { } public void createConditionalFormatterRules ( ) { } private List < XSSFConditionalFormattingRule > getOrderedRuleList ( ConditionalFormatting cf ) { } private int addBorderFormatting ( ConditionalFormatting cf , ConditionalFormattingRule rule , StringBuilder css , int cssIndex ) { } private boolean stopHere ( ConditionalFormattingRule rule ) { } private Object getFieldValWithReflection ( Object owner , String fieldName ) { } private boolean isBorderSet ( XSSFBorderFormatting borderFormatting , BorderSide b ) { } private boolean hasStrikeThrough ( FontFormatting fontFormatting ) { } protected void runCellMatcher ( ConditionalFormatting cf , ConditionalFormattingRule rule , int classNameIndex ) { } protected boolean matches ( Cell cell , ConditionalFormattingRule rule ) { } protected boolean matchesFormula ( ConditionalFormattingRule rule ) { } protected boolean matchesValue ( Cell cell , ConditionalFormattingRule rule ) { boolean isFormulaType = ( cell . getCellType ( ) ) == ( Cell . CELL_TYPE_FORMULA ) ; boolean isFormulaStringType = isFormulaType && ( ( cell . getCachedFormulaResultType ( ) ) == ( Cell . CELL_TYPE_STRING ) ) ; boolean isFormulaBooleanType = isFormulaType && ( ( cell . getCachedFormulaResultType ( ) ) == ( Cell . CELL_TYPE_BOOLEAN ) ) ; <START_BUG> boolean isFormulaNumericType = isFormulaType && ( ( cell . getCachedFormulaResultType ( ) ) == ( Cell . CELL_TYPE_FORMULA ) ) ; <END_BUG> if ( ( ( cell . getCellType ( ) ) == ( Cell . CELL_TYPE_STRING ) ) || isFormulaStringType ) { switch ( rule . getComparisonOperation ( ) ) { case ComparisonOperator . EQUAL : return cell . getStringCellValue ( ) . equals ( rule . getFormula1 ( ) ) ; case ComparisonOperator . NOT_EQUAL : return ! ( cell . getStringCellValue ( ) . equals ( rule . getFormula1 ( ) ) ) ; } } if ( ( ( cell . getCellType ( ) ) == ( Cell . CELL_TYPE_BOOLEAN ) ) || isFormulaBooleanType ) { Boolean formulaVal = Boolean . parseBoolean ( rule . getFormula1 ( ) ) ; switch ( rule . getComparisonOperation ( ) ) { case ComparisonOperator . EQUAL : return ( cell . getBooleanCellValue ( ) ) == formulaVal ; case ComparisonOperator . NOT_EQUAL : return ( cell . getBooleanCellValue ( ) ) != formulaVal ; } } if ( ( ( cell . getCellType ( ) ) == ( Cell . CELL_TYPE_NUMERIC ) ) || isFormulaNumericType ) { double formula1Val = Double . valueOf ( rule . getFormula1 ( ) ) ; switch ( rule . getComparisonOperation ( ) ) { case ComparisonOperator . EQUAL : return ( cell . getNumericCellValue ( ) ) == formula1Val ; case ComparisonOperator . NOT_EQUAL : return ( cell . getNumericCellValue ( ) ) != formula1Val ; case ComparisonOperator . LT : return ( cell . getNumericCellValue ( ) ) < formula1Val ; case ComparisonOperator . LE : return ( cell . getNumericCellValue ( ) ) <= formula1Val ; case ComparisonOperator . GT : return ( cell . getNumericCellValue ( ) ) > formula1Val ; case ComparisonOperator . GE : return ( cell . getNumericCellValue ( ) ) >= formula1Val ; case ComparisonOperator . BETWEEN : boolean lt = ( cell . getNumericCellValue ( ) ) >= formula1Val ; boolean gt = ( cell . getNumericCellValue ( ) ) <= ( Double . valueOf ( rule . getFormula2 ( ) ) ) ; return lt && gt ; case ComparisonOperator . NOT_BETWEEN : lt = ( cell . getNumericCellValue ( ) ) <= formula1Val ; gt = ( cell . getNumericCellValue ( ) ) >= ( Double . valueOf ( rule . getFormula2 ( ) ) ) ; return lt && gt ; } } return false ; } }

Fix:
boolean isFormulaNumericType = isFormulaType && ( ( cell . getCachedFormulaResultType ( ) ) == ( Cell . CELL_TYPE_NUMERIC ) ) ;